Along with the increase of a request of people for communication bandwidth, a Fiber-to-the-x (FTTx) technology obtains fast development, and the FTTx technology taking a Passive Optical Network (PON) technology as the principal thing is widely used.
A PON usually includes an optical circuit terminal mounted at a central control station and an Optical Network Unit (ONU) mated and mounted in each user occasion, and the ONU is provided with a modulating circuit for modulating a light emitting signal of the Distributed Feedback Laser (DFB) burst transmission circuit, and a laser transmitter driver chip for driving a laser transmitter to emit light.